Synthetic resin manufacture



Patented Dec. 28,

UNITED STATES PATENT OFFICE amazes smnn'rrc nasm maurscrunn Herbert o. Albrecht.

ation, of. Delaware No Drawing. Application July 18, 1934,

. Serial lhi 335,049

11 Claims. (i. zed-s) some cases approaching zero. A further object of This invention relates to polyhydric alcoholpolybasic acid resins, and more specifically to a method of producing resins of improved and desirable properties by special control and chemical action.

The usual resins oi the type just mentioned,

3 when modified with 50% or less 01' fatty oil, have, I

the disadvantage of exhibiting rather high acid numbers when used in solution as varnishes.-

, This high acid number basic pigments, such as zinc oxide, are apt to cause livering of paints and enamels using the resin as a vehicle.-

A previous method of means in practice that ing acid numbers comparable to those of natural resin varnishes, and containing not an-uiiduly large proportion of oil modifier, has been to use further modifying agents such as mono-basic acids of low molecular weight in place of part of the phthalic acid, or mono-hydric and dihydric alcohols inplace of some glycerine. Resins prepared in this way may have'the undesirable properties of being too soft or too expensive and the of low acid number require special closed apparatus for their manufacture. Another method by which acid numbers can be reduced somewhat is by use of an excess of This results in softening the resin and increasing its sensitivity to water, while the acid number is only with difllculty reduced even by a considerable excess of glycerine, due to unfavorable position of the remaining carboxyl groups relative to thesize and shape of the glycerine molecule.

A third method of reducing the acid number of these oil-modified resins is bythe addition '01 variousamino-compounds to the finished resin. This results often in increasing the viscosity of such resins in solution to an undesirable extent,

or in slowing up the oxidation of the drying oil which may be a. constituent of the resin, or in causing yellowing of enamel films in which the -resin is used, or producing other undesirable efiects in the complex paint mixture. In addition, suitable amino-compounds for the purpose are relatively expensive ingredients of the resin.

This invention has as an object the preparation of resins analogous to the usual modified and unmodifledglycerinemhthalic acid resins but with acid numbers very considerably lower and in obtaining varnish resins 15 of the poiyhydric alcohol-polybasic acid type havin polyhydric' alcohol-polybasic acid H this invention is to acteristics without usin pensive than phthalic various Iattyoils and Ronald A. McGlone, and Stephen John Roskosky, Flint, Mich to E. I. du Pont de Nem Del., a corpor assignors ours & Company, Wilmake resins of these charg ingredients any more exanhydride, g'lycerine, and oil acids.

A still further object is the production of resins of the polyhydric alcohol-polybasic acid type by veryrapid and cheap processes requiring only simple equipment.

These objects are' accomplished bythe following invention which consists in under the conditions hereinafter resin reaction,

conducting the pointed out, in the presence of controlled amounts of copper in solution in the resin ingredients.

The present invention in its preferred embodiment may be carried out in a very simple manner. 15

A small amount of co when both phthalic an stituents are present addition of the copper of making the particul some cases, the cop per may be added pper in the form of almost any organic salt is added to the resin at a stage hydride and alcoholic con- The exact moment of will depend on the method ar resin in question, and in with all the other ingredients at the start. This will be understood by those skilled in the art, to be further understood that the properties of the resin may also be controlled to some extent by and it is the choice or time for adding the catalyst. This is especially true when modifiers such as wood oil. which change independently of'the esteriflcation reaction, are to be treated to a certain desired degree.

The reaction of the hydroxylic constituen phthalic anhydride with the ts is then carried out preferably at a temperature between 425-500 F., and,

if desired, in open kettle as high as 540 s-by the simplest possible methods. Temperatures as low as 390 F. and

F. sometimes, though not always,

produce the desired result, but a definite eflect of the copper is increasingly apparen F. and even higher.

usually noticeable. The efiect is' t at temperatures up to 520 Temperatures above 500 F.

are, however. undesirable for a number of reasons,

chief ofwhich are the atsuch temperatures ing resins .of undesira The addition of fr per calculated as volatility of the ingredients and the likelihood of formbly low molecular weight. 45 om 0.002% to' 1.0% of copmetal, based upon the total weight of the resin ingredients is in most instances amount does not aife process but amounts 0.3% are unnecessary color of the finished the objects of the invention.

More than this maximum ct the operativeness of the substantially in excess of and aiiect materially the The method of practising our invention is illustrated by the following examples:

Example I Charge into a kettle of Monel metal the following: Chinawood oil "lbs-.. 96 Linseed oil lbs 96 Glycerine lbs 40 Caustic soda oz 7 Heat, covered, at 480 F., six minutes with thorough stirring. The material should be homogeneous. Add: I Phthalic anhydride lbs 160.8 Copper acetate ozs l4 Heat to 450 F. Add: Glycerine lbs 28 Hold at 460 F. with stirring about three hours to an acid number of 10. This proportion of ingredients ordinarily gives a resin of very high acid number (over 60).

Example 11 Charge into a stainless steel kettle:

Cocoanut oil 4.00 Glycerine .80 Caustic soda .04

Heat at 470 F. until homogeneous. Add:

. Pounds Phthalic anhydrlde 4.64 G-lycerine 1.17

Bring to 425 F. and add Copper oleate .09

Hold at 450 F., about two hours with stirring to an acid number of 2. A holding time up to six hours may be required without copper to attain a low acid number, depending on the amount of blowing with inert gas.

Example III Pounds Linseed oil acids 33.6 Glycerine 24.7 Phthalic anhydride 50.3 Copper acetate .03

The ingredients are placed i a suitable metal container, made, for example, of aluminum, Monel metal, stainless steel, or even of iron if color is not an important factor. They are brought to a temperature of 480 F. and held there until the acid number is below 5. With stirring, the holding time should be less than two hours. During the course of the resin reaction the meltturns from green to colorless, then to brown, and finally at low acid number the copper is usually precipitated in the finely divided metallic state.

A resin with an acid number below 10 is generally satisfactory for use even with very reactive pigments. made without copper, would tend to gel with an acid number of about 50 and might even give difilcultles in making at all under practical conditions and at the given temperature.

Example IV I Grams Phthalic anhydride '70 Glycerine; 16.5 Diethylene glycol 22.5 Copper acetate .22

Pounds act as a catalyst, in

inorganic compounds of copper are generally "ly practised through the The resin of the example above, if

Heat at 470 F. in glass or stainless steel about hour to acid number of 5. Without copper, the resin will gel. acetate may also be added at the start.

The action of the copper in the present process appears to be enhanced by the presence of alkaline material. For this reason the manufacture of oil modified resins by the process of Examples I and II, which involve the alcoholysis of the oil by treatment with glycerol in the presence of sodium If desired, .11 gram of sodium,

hydroxide, is particularly advantageous in the practise of our invention. Alkaline metal salts are particularly effective as will be seen from the fact that the substitution of litharge as the alcoholysis catalyst for the sodium hydroxide of Examples I and II reduces materially the action of the copper. The maximum effect of the copper is produced when about one atom of alkali metal is present for each atom of copper. In

some instances, alkali metal may be present in small amounts as an impurity in the glycerine, oil acids, orother resin ingredients, and for this reason may cause a more pronounced effect on the copper.

We prefer to add the copper as cuprlc acetate or cupric phthalate. The objects of the invention may be accomplished, however, by the use of any copper compounds in solution in the resin ingredients in the presence of oxygen. In fact, it is possible to use predetermined amounts of metallic copper which react with the resin ingredients to produce a solution of copper in such quantity as to give the results desired. The copper to be effective must of course be in solution during the synthesis of the resin, and this means necessarily that the copper is finally present in a state of organic combination. Copper as metal can only be dissolved by the resin, and therefore the presence of oxygen. The

satisfactory. Those not recommended, particularly in commercial practice, are those not readily acted upon by phthalic'acid, as for instance salts of strong or non-volatile acids, i. e., the chloride and sulfate. The copper may be used in any original form whatever so long as it ultimately dissolves in the resin. We desire it to be understood, therefore, that our invention consists in carrying out the resin reaction in the presence of copper compound in solution under controlled conditions rather than in the particular kind of copper containing material added to the reaction mixture.

The invention is from the standpoint of consistent'duplication of results most advantageousdirect addition during the resin synthesis of the organic copper compounds inasmuch asthese are generally easily soluble in the resin reaction mixture. The use of metallic copper or of inorganic copper compounds, however, is not precluded. Thus, satisfactory results may be obtained by adding uniformly powdered copper or ground copper oxide to the resin ingredients in the batch. In this case the ratio of copper in solution in the form of organic compound to the resin ingredients is regulated to provide throughout the heat treatment of the resin ingredients the required amount of copper, which as stated above is usually calculated as metal.

It is also possible sults disclosed herein by carrying out the resin reaction in a'copper kettle and adjusting the various factors of the reaction, including that of to obtain the improved re-- 2,103,255 batch, the copper surface exposed, its cleanliness,

the amount of air permitted to .reach the-resin charge, etc., so that the copper from the container will by reacting vide the regulated quantity of copper mentioned above. Thismethod, however, is far more difficult to controland less practical because of the reater difficulty in attaining the object of our invention, namely, the consistent duplication of results in the manufacture of resins of low acid in accordance with the prior art practise and the lack of knowledge of the effect of copper, the amounts of it required, and the proper temperature of reaction have heretofore made the use of copper kettles a commercial liability rather than an advantage. .2

It will be seen from the foregoing that our indown to the Substances present in the melt do, however, exert a reducing eflect on the copper and, in some special cases, it may be desirable to counteract this by the controlled admission v of air during the reaction. The resin ingredients include phthalic acid orv anhydride, the polyhydric alcohols, and modifying ingredients; usually used in making resins of by the examples, the oil modified resins, with which the present invention is oil acids as the substances containing the-fatty oil acid radicals which in conjunction withithe particularly useful, are madefrom eitherthe fatty oil or the fattyrequired to make thereslns.

phthalic anhydride esterify the polyhydric alcohol. Other useful polyhydric alcohols are glycol, sorbitol', pentacrythritol, diethylene glycol, trimethylene glycol; propylene glycol,"dig lycerol, higher polyglycols and polyglycerols. Resins made by the present process with polybasic acids other than phthalic acid, which in the appended claims means the anhydrlde as well as the acid itself, are not generally afiected required degree, possibly because the copper salts by thecopperto the of other polybasic acidsare not sufficiently soluble in the melts. Thus, while some decarboxylation of maleic acid occurred with copper in the presence of p tassium and a trace of action on crude sebacic a id, no apparent effect was found on the resins when they were made acid number will not be obtained. j

A large variety of copper compounds cther than those mentionedwill suggest themselves to those skilled in the art. Examples of'these,

\ which are conveniently cupric rather'i'than cup'rous, are formate. acetate, phthalate, butyrate,

laurate, palmitate, stearate, oleate, linoleate,

The uses of this invention .wlllcommend themselves to all those familiarwith the requirements hardening of the applied film. The use of drying oils, especially China-wood oil, to modify polyhydric alcohol-polybasic acid resins, results commonly in an inability to obtain vehicles usable skill of the varnish -jects and tends to counteract any loss in water resistance due to softness. Commercial our process have a Iflnal acid number of at least less than 11 they were made without the presence of copper as described herein. Anotherv important advantage is'the reduction in the time special commercial process have un; 1'

This is pa ti ul 7:!

1. A process for making resins of low acid number which comprises heating to resinification a reaction mixture of phthalic anhydride and glycerol in the presence of 'a copper compound in solution in the reaction mixture, said compound containing not less than 0.002% copper based upon the weight of the reacting ingredients, and thereby producing a resin having an acid number at least 50% less than a resin similarly made in the absence of said copper compound.

ber which comprises 2. A process for making resins of low acid numbr which comprises heating to resiniflcation at a temperature not less than 425 F. a reaction mixture of phthalic anhydride and glycerol in the presence of a small amount of an alkaline compound arid in the presence of a copper compound in solution in the reaction mixture, said compound containing not less than 0.002% copper based upon the weight of the reacting ingredients, and thereby producing a resin having an acid number at least 50% less than a resin similarly made in the absence of said copper compound.

-3. -A process for making resins of low acid number which comprises adding to a reaction mixture of phthalic anhydride and glycerol an organic compound of copper soluble in said reaction mixture, said compound f containing not less than 0.002%,copper based upon the weight of the reacting ingredients, and thereby producing a resin having an acid number at least 50% less than a resin-similarly made in the absence of said copper compound.

4. 'A process for making resins of low acid numheating to resinification phthalic anhydride, glycerol, and a substance of the group consisting "of fatty oils and fatt'y'oil thereby producing a resin acids in the presence of a copper compound in solution in the reaction mixture, said compound containing not less than 0.002% copper based upon the weight of the reacting ingredients, and containing not more than 50% combined fatty oil having an acid numher at least 50% less than a resin similarly made in the absence of said copper compound.

5. The process set forth in claim 1 in which the heating is at a temperature above 425 F., and the amount of copper is from 0.01% to 0.3%. 6. The process set forth in claim 3 in which the heating is at a temperature above 425 R,

and the amount of copper is from 0.01% to 0.3%. '7. The process set forth in claim 4 in which the heating is at a temperature'above 425 F., and the amount of copper is from 0.01% to 0.3%.

8. An oil modified synthetic resin of low acid number comprising in chemical combination substantially chemically equivalent amounts of resin forming ingredients consisting substantiallysolely of glycerol, phthalic anhydride, and the oil acids contained in fatty oil and obtainable by heating to resinification a reaction mixture of said ingredients having dissolved therein a copper compound containing not less than 0.002% copper based upon the weight of the reacting ingredients, said resin containing not more than about 50% combined oil and having an acid number at least 50% less than a resin made solely from said-ingredients in the absence of said copper compound. 9. A coating composition comprising -a basic pigment and the resin set forth in claim 8.

10. A coating composition comprising zinc oxide and the resin set forth in claim 8.

11. A process for making resins of low acid number which comprises adding to a reaction mixture of .phthalic anhydride and polyhydric alcohol an organic copper salt, and heating the reaction mixture to resinification, said copper salt being soluble in the reaction mixture and being present in amount calculated as metal not less than about 0.002% based upon the total weiglit of the resin ingredients.

HERBERT O. ALBRECHT. RONALD A. MCGLONE. STEPHEN JOHN ROSKQSKY. 

